Three years prior, Dillon and her boyfriend Sam Scudder teamed up with Leonard Snart for a heist. After the heist was successfully finished, Snart advised the two to lay low for a while and not to throw out the money immediately.
However, Scudder did not listen which annoyed Snart. Not happy with Snart's rules, Scudder and Dillon claimed that they wanted out. This prompted Snart to attack, attempting to kill Scudder with his cold gun. Scudder anticipated this move and rushed forwards to disarm Snart. During the struggle, Dillon defeated Snart's henchman but Scudder was knocked down by Snart. Scudder fell onto a mirror and Snart picked up the gangster's gun, aiming it at Scudder's head. Before he could pull the trigger, the particle accelerator at S.T.A.R. Labs exploded, frightening Snart, who fled with his men without finishing off Scudder. Scudder and Dillon, who both remained behind in the warehouse, were struck by the dark matter released in the explosion and were both transformed into meta-humans. However, while Dillon remained relatively unharmed, Scudder was drawn into the mirror. Believing him to be dead, Dillon fled the scene.
Dillon, currently imprisoned at Iron Heights, is visited by Detective Joe West who tells her that Scudder is back. While Joe is talking, Scudder appears by morphing in through the glass window, grabs Dillon and escapes with her. Back in their hideout, Scudder proposes that the two of them take over the city as no one would be able to oppose them and Dillon tells him about the existence of the Flash.
The two start robbing banks again, with Rosa disposing of all guards by using her powers to throw them into a vertigo-high. While the hallucinating guards are lying on the ground, Scudder and Rosa are about to escape. However, they are confronted by the Flash and Jessie Quick. Scudder is surprised, claiming that he heard much about Barry. The two then enter a nearby window and make their escape, but Barry and Jessie follow the reflection, knowing that the two are forced to leave the reflection eventually. The two speedsters pursue Scudder and Dillon over the glass window panes of Central City's skyscrapers. The two eventually separate, while Barry pursues the reflection of Scudder, Jessie confronts Dillon. When Dillon uses her powers to drug Jessie, causing her to fall of a rooftop, Barry is forced to cease his pursuit of Scudder to catch his fallen friend. Back on the ground, Barry is surprised by Scudder who grabs him, shoves him into a glass wall and traps him inside. Before escaping, he wishes Jessie good luck getting Barry out of the window.
Scudder and Top are later seemingly called by Leonard Snart, who arranges a meeting in a hall of mirrors of a nearby amusement park. However, when battle ensues it is revealed that Snart was merely a hologram. Jessie and Barry reveal themselves. While Top tries to use her powers on Jessie again, Jessie overcomes the effects and knocks out Dillon easily. She is presumably imprisoned at Iron Heights afterwards.
When Barry runs off into the future, to 2024, in order to learn the identity of Savitar, he finds that Mirror Master and Top are still a major criminal force in Central City. The moment Barry arrives in the future, he is found by Top and Mirror Master. Top uses her powers to desotientate him, causing him to stumble around. Mirror Master then emerges from a glass panel and punches Barry to tge ground. While Barry is still on the ground, Mirror Master starts kicking Barry, claiming that Central City belongs to him. However, Barry swiftly regains control, knocks both villains to the ground and speeds off, having more important things to take care of.
During his time in the future, Barry brings the formerly disbanded Team Flash back together. When Mirror Master and Top commit a robbery in a jewelry store, they are confronted by Barry. The two are annoyed, claiming that they warned Barry to stay away from them. Top uses her powers on Barry once more, disorienting him, and Mirror Master uses his powers as well to further add to Barry's confusion. However, Barry is aided by the Barry from 2024 who uses a device which counter-acts the villains' powers. Realizing this, the two run off and split up. Top is pursued by Barry from 2017 and swiftly chained up and later delivered to the police. Mirror Master and Top are then incarcarated once more.